Starting from today Blizzard has added - on a purely experimental basis - a new co-op mode to Hearthstone: Heroes of Warcraft, and it's called "Unite Against Mechazod".
In this new mode players can join forces with a partner in order to defeat Gearmaster Mechazod, and they can do so using some pre-built decks.
The most interesting part of this co-op mode is that if one of the two players is defeated by Mechazod, it'll be "game over" for all. Therefore, it's going to be essential that both players work together, using cooperative strategy to keep on top of their opponent (who will have two attack points and 95 health points).
You can try Unite Against Mechazod between November 4 - 9. For further details, please visit the official blog.